Upgrading the Memory in a Cisco 2500 Series Router

Introduction: Upgrading the Memory in a Cisco 2500 Series Router

Wanna upgrade to that new IOS version to actually make your 2500 series Cisco router useful for something again but can't because you don't have enough RAM? I'll show you how to upgrade the RAM and where give you some advice on where to find some to upgrade to!

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Step 1: Find Your Replacement RAM

First off, you're going to need to find the RAM you'll be upgrading TO, keeping in mind that the Cisco 2500 Series has only one slot for RAM and does not support sticks bigger than 16MB.

Your two main options here are:
A) Purchase some probably overpriced Cisco RAM.
B) Find a really old computer than still uses the 72-pin SIMMs and rip a (non-EDO) stick of RAM out of it.

I chose the latter as I still have several computers old enough to be using this RAM strewn about and settled on this lovely 16MB stick of RAM. The thing to note here is that it is:
- 16MB or less
- Has 72 pins (split equally into halves)
- Is not EDO. I don't know how to tell this from looking at it, I just already knew it wasn't ;P

Step 2: Remove the Screws

You're going to need to start by removing the screws. There should only be one, or 3 if you have the rack mount brackets on it.

If you have the rack mount brackets, you need only remove the top screw(s), you can leave the bottom ones on.

Then, look at the bottom of the router near the back (side with the ports) and find the lone screw and remove it.

Step 3: Prying the Case Loose

Getting the case off is probably the trickiest part of this whole thing.

What you need to do here is get a pretty big flat blade screwdriver and put it into the marked pry slots and pry (by twisting it. don't bend the metal). And then use some un-official pry slots and pry some more. Then probably pull at it with your hands a bit.

It's going to probably take a bit of work, but just do it. Don't worry about bending or marking up the metal a bit... it doesn't matter how it looks, it's still going to route slowly and not support 802.1Q encapsulation.

Step 4: Get the Case Off

Once you get the case pried loose so that it's pulled clear of the other half, it's simply a matter of lifting it off.

Step 5: The Internals

The inside of the router. Sure doesn't look very complicated for what these things would cost new :)

You'll notice in the pictures the slots on the left labelled "Flash". These are the flash memory which in the 2500 series is used to store the currently installed IOS along with (sometimes) configuration backups and other misc. stuff. You can install two sticks at a maximum of 16mb each I believe. They do not add together, so having two 8mb sticks does not allow you to install a 15mb IOS, it simply allows you to install an 8mb IOS and store a bunch of configuration backups.

The DRAM slot is exactly that. The slot where the RAM goes. Cisco routers simply use 72-pin SIMMs.

Keep in mind that the flash memory sticks and RAM sticks are NOT THE SAME. You cannot interchange them. They will not even properly fit in each other's sockets, so you will have to try REALLY hard to screw this up.

Step 6: Remove the Old Ram

What you need to do here is:
- Place your index fingers on the back of the stick of RAM.
- Place your thumbs on the little silver clips on either side.
- GENTLY apply pressure to the back with your index fingers, pulling it forward while simultaneously pushing the clips outward with your thumbs.
- The RAM is free, just lift it out.

Step 7: Insert the New Ram

Take your new stick of RAM you're upgrading to, and find the notched out side (it's pretty obvious, especially with the pictures). You're going to install it with that notched out side facing to the left (the side facing the flash memory slots).

To install it, gently set the stick of RAM into the slot with the pins down and the notch on the left. Then, while still mainting enough downwards force to keep it from slipping out of the slot (should hardly be any) push it backwards until you hear a CLICK and both of the metal clips are holding it in place.

Step 8: Reassemble the Router

At this point you've really got two options:
- If you're sure that the RAM will work, then continue on with this step and reassemble the router.
- If you're not sure and would like to test it before getting the router all reassembled again, then skip to step 9 and come back here once you know the upgrade worked.

Do the reverse of the first few steps :)

Take the case, set it back on the router making sure that all the parts that look like they should be out are out and look like they should be in are in. Make sure to set it on a bit back from 'in place' so that you can slide it into place.

Once you've got the case on the router, slide it back on tight, then replace all the screws you removed.

Step 9: Test!

Grab your console cable, hook up the router and see how much RAM you have!

If it says something ridiculously low like 1MB or 2MB, then it probably means that it doesn't recognize your stick and is only using the on-board memory. The only reason I've found for it not to recognize the memory so far is that it's (a) too big or (b) EDO. If neither of those apply just try another stick of RAM.

Anyways, cheers! Enjoy your newly upgraded router!

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    6 Discussions


    10 years ago on Introduction

    I just grabbed one of these beasts for $10, and hopefully find out that its 100% working tomorrow. If so, I'll run back after class and grab me another!


    Reply 10 years ago on Introduction

    Heh, good plan. Picked up two (I think they're) 2521s off of E-Bay for $20 each almost a year ago. Shipping was a bugger, but I have been using one since as my main router. Instead of some cheap consumer crap, I have my old Cisco doing DHCP, NAT, etc. Awesomely reliable, cheap and a lot more fun :]


    11 years ago on Step 9

    If you install two 8MB flash modules in a Cisco 2500 you can use a 16MB image. I don't think they ever made anything but 8MB flash modules for the Cisco 2500, so if both slots are populated, you have 16MB of flash. show flash will tell you how much flash you have and what's in it.


    Reply 11 years ago on Step 9

    I tried installing two modules, but it would not treat them as a single file system, but as two seperate file systems, meaning I could not store a file greater than 8MB. Was there something I had to do to get it to treat it as a single filesystem?


    Reply 11 years ago on Introduction

    You need to use the - partition flash 1 - command (I did it in ROM mode but I think you can use it in normal mode too) - Dan


    12 years ago on Introduction

    Oooooooooooreos have nothing to do with this Instructable. Nice job!